Prince Oi (乎非王)
Prince Oi (Oi no Kimi or Oi no Miko, his date of birth and death were unknown) first appeared in the Itsubun (unidentified or lost writings) written articles of the 'Joguki' (Record of the Crown Prince) being an Imperial family (Royal family) around the fifth century in Japan
Editors and authors of the "Kojiki-den" (Commentary on the Kojiki) often miswrote Prince Oi (乎非王) as "宇非王" (also "宇斐王") in their transcription of the text, and this was incorrect.
Prince Oi's father was Prince Ohodo and the mother of Prince Oi was 'Nakashi no Mikoto.'
Additionally, Prince Oi was a great-grandchild to the Emperor Ojin; he was a nephew of Oshisakano Onakatsunohimeno Mikoto; and the grandfather of the Emperor Keiti. Prince Ake (Ake no Miko) and Prince Tsukimeka were assumed to be the paternal half brothers of Prince Oi. Prince Oi married Kuruhime no Mikoto, who was a daughter of Mugetsu Kuni no Miyatsuko Ijimura Kimi, and she would give birth to Prince Ushi (Ushi no Okimi; also known as Hikoushio).
The written names of Prince Oi were entered in the thirteenth volume of the "Shaku Nihongi" (annotated text of the Nihon Shoki), as cited by the Itsubun (unidentified or lost wirings) genealogy from the 'Joguki'; there were no episodes of achievement or events on Prince Oi found in this historic book.
If we trace only the direct lines of genealogy for Prince Oi from the Joguki, it could be written this way: 'Homutawake no Miko –Wakanuke futamata no Miko – Oiratsuko (Ohodo no Okimi)– Oi no Okimi – Ushi no Okimi – Odo no Okimi.'
Each of these names can be identified as follows: 'Homutawake no Miko' was the Emperor Ojin; 'Wakanuke futamata no Miko' was 'Wakanoke futamata no Miko'; Oiratsuko was 'Ohodo no Okimi'; 'Ushi no Okimi' was 'Hikoushio' (also pronounced 'Hikousi no Okimi') and 'Odo no Okimi' was the Emperor Keitai. However, according to recent historical research and studies, the original genealogy might be written like this: "the Emperor Ojin – Oi no Okimi - Ushi no Okimi – the Emperor Keitai" which extended into two generations, was eliminated from the six generations of the genealogy as described in the Joguki: Wakanuke futamata no Miko and Oiratsuko (Katsuyasu KAWAGUCHI). Whether or not it is true in each case, there is no confirmed evidence to support Prince Oi as a royal family with a lineage line to Ojin.
Additionally, this grandfather of the Emperor Keita was written as 'Shi (or Oi) no Okimi' in historical books and genealogy tables during the Medieval Period; such as: "Mizu Kagami" (Japanese historical book); "Gukansho" ("Jottings of a Fool"; a Japanese historical book written by Jien, a Buddhist priest of the Tendi sect.); the "Jinno Shotoki" ("Chronicles of the Authentic Lineages of the Divine Emperors"; a Japanese historical book written by Chikafusa KITABATAKE); and the "Honcho koin jounroku" (family tree charts of emperors and imperial families in Japan). As to 'Shi (or Oi) no Okimi' in those historical books, there were no previous examples of ancient writers or editors using 'Shi (私)' for Manyogana (early Japanese syllabify composed of Chinese characters then used phonetically); so historians and other scholars would be able to conclude that the original writing was written in this way 'Oi no Okimi' and 'Shi (or Oi) no Okimi' was the transcription mistake. Furthermore, Oi no Okimi was another written expression for Prince Oi, "so we can safely indentify "Shi (or Oi) no Okimi" in those historical books as Prince Oi." Since there were different writing expressions used for one person in historical books, we can also consider that there were possible historical materials which existed to support the origins of the family tree chart for the Emperor Keitai, other than the 'Joguki' (For example, family tree charts of "Nihonshoki" [Chronicles of Japan]).